The promotion is probably the work of Kim Jong Un's uncle, an expert says

North Korea said Tuesday that it had promoted a little-known general to a key military rank, a day after it announced that it had relieved its army chief of all his government posts.

The secretive state's top two military commissions have decided to give the title of vice marshal to Hyon Yong Chol, according to a report by the state-run Korean Central News Agency (KCNA).

The KCNA report did not say whether Hyon will replace Ri Yong Ho, the departed army chief. Ri held the title of vice marshal along with other military and party posts before his removal.

North Korea said Monday that it was relieving Ri from all his posts due to an unspecified illness. The news prompted speculation among analysts that there might be a power struggle between North Korea's powerful military and civilian elite.

Kim Jong Un became "supreme leader" of North Korea after the death of his father, Kim Jong Il, in December.

Ri -- who was appointed army chief in February 2009, according to KCNA -- was considered one of Kim Jong Un's closest aides during and after his rise to power.

There are several other vice marshals in North Korea at the moment. Those holding the title are considered to be eligible for key posts in the upper echelons of the ruling Workers' Party of Korea.

Not much is known about Hyon, but his promotion is probably the work of Kim Jong Un's uncle, Jang Song Taek, an influential figure behind Kim's rise, according to Park Soo-geun, a former commander of the South Korean Defense Intelligence Command.

"He was promoted in 2010 to the rank equivalent to that of four-star general together with Kim Jong Un," Park said of Hyon.

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"But being promoted to vice marshal means he will now show off his power at the political stage," Park, a retired South Korean major general, added.

Andrei Lankov, a professor at Kookmin University in South Korea, agreed with Park's assessment.

"This follows a pattern we have seen since at least last March," Lankov said. "People who can be described as the Jang Song Taek group are taking the upper hand. It seems Jang Song Taek may be removing people who might constitute a threat to him."

If so, this may be the the first purge under the leadership of Kim Jong Un, Lankov said.

"Not necessarily a bloody one but the first case of a person of great political significance being removed," Lankov said.

Korea observers may soon find out what's happening inside the secretive nation, said Han Park, a professor of international affairs at the University of Georgia and director of the school's Center for the Study of Global Issues.

"If it is a power struggle of that nature, we will see some ensuing changes in top personnel," he said. "Unless we see that, (Ri's stepping down) is really for personal reasons, such as illness."

Park said he saw Ri in April at a banquet in Pyongyang celebrating the 100th anniversary of the birth of the nation's founder, Kim Il Sung. "He didn't appear to be a very healthy person," Park said. "His kind of color is a little dark, and it didn't appear to be very healthy."

Still, he said, he was "shocked" when he heard the news that Ri had been removed from his posts.